Skylights have been installed in buildings and vehicles of various types but a practical, economical and leak resistant skylight for a railroad boxcar which also provides resistance to unauthorized entrance has, so far, eluded railroad car manufacturers. The failure to provide a practical skylight for a railroad boxcar may be due to the nature of the roof structures of railroad boxcars and because of the demanding service to which railroad cars are subjected. A conventional boxcar roof is assembled of rectangular sheets of 12 or 14 gauge galvanized steel which have been strengthened with pyramidal corrugations to form roof panels. The roof panels, which are preformed, are positioned on top of the boxcars with the longer dimension of each panel extending between the side walls of the cars. The panels are then connected by rivets and roof seam caps provided over adjacent edges of roof panels to prevent leakage.
This invention is directed to a standard size roof panel of galvanized metal for installation as a portion of a roof of a railroad boxcar which panel incorporates a pair of skylights. The roof panel of this invention can be economically preformed and assembled on a boxcar using conventional assembly techniques. Since it is a conventionally sized panel, it can be interfitted with other standard boxcar roof panels so as to locate the skylights adjacent the ends of the car as required to provide adequate lighting inside the boxcar. The skylights must not unduly reduce the strength and rigidity of the roof panel in which they are provided and must provide long term resistance to water leakage and resist unauthorized entrance to the boxcar.
An object of this invention is a standard dimensioned boxcar roof panel having leak resistant skylights formed therein which leak resistance is obtained without the use of caulking.
Another object of this invention is a roof panel for a railroad boxcar containing skylight openings in which these openings are located in low stress regions of the roof panel.
Another object of this invention is a roof panel containing skylights in which it is necessary to eliminate only one pyramidal corrugation of a conventional roof panel to install the skylight openings.
Yet another object of this invention is a skylight assembly having a gasket extruded from an EPDM polymer with a solid inner core located at the center of a pattern of bolts connecting the gasket to the roof panel.
Still another object of this invention is a sealing arrangement for a polycarbonate skylight window in which a polycarbonate window is seated in a notch in an EPDM polymer gasket and the gasket is clamped by a clamp ring by a pattern of lock bolts arranged around the gasket.
Yet another object of this invention is a railroad car roof panel containing skylights which retains most of its original stiffness by the installation of clamp rings around each skylight opening to replace the stiffening effect lost by removal of sheet metal for the skylight openings and removal of the corrugation normally formed in the area of the panel now occupied by a skylight.
An additional object of this invention is a skylight for a boxcar roof having a window portion which may be either flat or domed.
Another additional object of this invention is a skylight for a boxcar which limits the passage of ultraviolet light into the boxcar.
A further additional object of this invention is a skylight which resists unauthorized removal of the window.
An additional important object of this invention is a skylight for a boxcar which can be used in a wide range of ambient temperatures without leakage of water into the boxcar.